The present invention relates to the separation of metals from metal salts and more particularly relates to the separation of metals from fused salts by electrochemical or electrowinning processes.
It is known to separate certain metals from their salts by electrolysis of the molten electrolyte for example, the individual separation of aluminum may be achieved by the electrolysis of a molten solution of alumina in cryolite (the so-called Hall-Heroult process). An alternative process for the production of aluminium involves the electrolysis of molten aluminium chloride using a bipolar cell. Also magnesium may be produced by the electrolysis of molten magnesium chloride in a bipolar cell as disclosed in European patent numbers 0096990 and 0101243.
Requirements for the efficient production of metals by electrolysis of their molten salts include a cell having a low tendency for the products of the electrolysis to recombine and a low electrical internal resistance. The tendency for recombination may be overcome by the interposition of a diaphragm to separate the anode and cathode. However, the presence of the diaphram tends to internal resistance of the cell.